I caught some bad bearings in my ideler pulley before they siezed.

ATI doesn't sell replacement bearings, just pullies and tensioner units. But the bearings used are a common bearing for automotive compresors and altenators.

The pulley uses two bearings in a stacked arangment, they are both the same.

Part number FAFNIR 203 V V

Available at good auto parts stores for $10 -$12.

If your tensioner pulley has any play, remove the pulley from the arm, and inspect the seals. There is a snap ring on the back of the pulley. After you remove it, the bearings slide out with out too much effort.